PARIS—The faithful stood, chanting Laurent Lokoli’s name, stamping their feet, shaking the flag of Lokoli’s native Corsica, the Bandera Testa Mora (Flag with Head of Maure), before their hero even walked out onto the court for the warm-up. The white flag bears the profile of a black man, hair girded in a headband, and if you never ate your corn flakes off one of those “flags of the world” placemats, you might have surmised that some loyal fans had invented this banner purely to pay tribute to Lokoli.

As his opponent, Steve Johnson of the United States, walked over to his own chair, he could have been forgiven for thinking less of getting his own profile on a banner than avoiding getting his head impaled on a stake. The French crowd was going nuts for the energetic, 6’2” 18-year-old nicknamed “El Loco,” and that’s a dangerous combination.

Lokoli was ranked just No. 402, but he received a wild card into the qualifying event. Johnson knew that Lokoli had survived a match point as he made his way into the big show. He had also, along with about 1.6 million other YouTube viewers, watched the dance-off between El Loco and Gael Monfils during a charity event at Roland Garros the day before the tournament started.

Johnson, ranked No. 64, understood that probably half of France had fallen in love with this emotional and telegenic kid who had built such a commanding lead yesterday before light failed and the conclusion was postponed. And they desperately wanted to see him win this one.

But Johnson also knew that he was walking out there today with a 3-1 lead in the fifth set.

Thus, he knew that no matter how much they chanted and clapped, or how overwrought Lokoli became while trying to please them, Johnson himself had made an incredible comeback and now had a simple job to do.

“I knew I had to come out and kind of close the door.”

The backstory for this first-rounder, which took place on Tuesday, is complicated, but here are some salient points: Lokoli was on fire early in the match. He won the first set and had six set points in the second before he took it in a tiebreaker, 9-7.

Tough as it was to lose that set, extending it allowed Johnson to get a toehold in the match, and he continued to cling and survive. Johnson dismissed two match points in the third set, and he pulled it out, 7-6 (3). He rolled through the fourth, 6-3, and sensing that the tide had turned, he went up a break to 3-1 in the fifth before the match was called off due to darkness.

Oh, I almost forgot. Johnson knew something else.

Last week, in Nice, it was he who had match points, but failed to convert them, in his first-round clash with Dominic Thiem. Johnson served for that match three times and still lost it.

“I knew you're not out of it until you're out of it,” he said after today’s conclusion. “It was just kind of a learning experience last week, and I used it this week and just kept fighting.”

For his part, Lokoli had spent a restless night after failing to take either match point. “It was difficult for me to sleep last night, because even though you try not to think about it, it's difficult. I was not very happy. I knew I had many opportunities. I should have played them differently. But then I managed to tell myself that this was behind me. There was nothing I could do about it. I had a match that I needed to finish.”

So there they were, starting over, with Johnson in possession of a mulligan of sorts. Both men appeared nervous during the warm-up, and who could blame them? The crowd packed into that delightful Court 7 was humming with pent-up energy, carrying on while they watched every shot as if it counted on the scoreboard.

One lone voice, belonging to a fellow named Tom Bender from Baltimore, rang out for Johnson, “Come on, Steve,” he bellowed. “You can do this!”

The crowd for Lokoli, it wasn’t composed entirely of fickle Frenchmen. “There were many people who came from Corsica to support me,” Lokoli would explain. “I said the other day they would come and support me, and they did. And they were very loud, and I liked it very much.

“I love this island of mine. I love it. And seeing all these people, they came all the way. They had no return ticket to go back home. They came with just a single ticket to get to Paris. . . I'm so proud. It's a unique moment for me, and I want to thank them from the bottom of my heart.”

But as nice as it is to be the favorite of the crowd, there’s a point at which the price it asks may be just a little too high. Lokoli knew what the fans longed for, and they were no more inclined to factor the score into their wishes than a kid is to consider price when he makes up his list for Santa. Before they resumed, Lokoli looked at the area where his most voluble supporters stood chanting and made a scary face, clenching his arms in the parenthesis favored by bodybuilders. They roared their approval.

Lokoli opened the resumption with a service winner, and he went on to hold—as did Johnson. Lokoli held again for 3-4, and by then the pattern was evident: Johnson would be patient, essentially signaling that if Lokoli wanted the match, he’d have to reach out to the frontiers of his game to take it. Lokoli likes to crack the forehand, and Johnson did everything in his power to break down his less menacing backhand.

“I got a little bit away from what was working early in the match (yesterday),” Johnson admitted. “And then I went back to his backhand towards the end of the day. I just kind of kept fighting and giving myself every chance I had.”

Johnson did a masterful job playing within himself while pressuring Lokoli. He handled the atmosphere with composure bordering on nonchalance. Some players get a hate on, often irrationally, for a crowd that’s heavily invested in his opponent. Not Johnson.

“I try not to fight the crowd because I don't know how many people are out there,” Johnson said, somewhat enigmatically. “They were loud. That's the way it should be. It's great for him and great to get behind a French kid like that. You just stay calm and go about your business and not let it affect you in a negative way.”

Johnson’s equanimity paid off. He held for 5-3, and knew his life would be a lot easier if he broke to win the match. He returned well and kept the ball in play, which was mainly what it took. And Johnson ended it on his second match point, when he pushed Lokoli over the the backhand corner and then whacked an inside-in forehand winner. The match clock read 3:57.

Lokoli turned to the Corsican contingent in the crowd the moment the score was called, his face as expressive as one of those Greek theatrical masks signifying tragedy. Meeting Lokoli at the net for the handshake, Johnson winced and barely refrained from shrugging, “sorry.” They stood for a split second and then they embraced. It was nothing less than a wonderful moment that left you smiling—and thinking better of both men.

At least a lot of those Corsicans won’t be going home disappointed. There are certain advantages to the one-way ticket.